Research Shows Responses to Flexion Tests can be Measured

Flexion testing, using the sensor-based system, at the University of Glasgow's School of Veterinary Medicine.

Photo: Courtesy Image

For many years, opinions on the value of flexion tests in assessing equine lameness have been divided, but now new research looks set to turn what has always been regarded as a subjective process into an objective one. The comprehensive study, recently published in Equine Veterinary Journal (EVJ) in partnership with the American Association of Equine Practitioners, has shown that a wireless, inertial sensor-based system can effectively measure the horse’s response to a flexion test.

Flexion tests are used routinely in horses with subtle or imperceptible lameness, to exacerbate the problem and make it apparent to the observer. The test involves applying a short period of pressure to the joints of the limb before re-examination, and evaluating any change in gait. However, flexion tests rely on the ability of the observer to identify and interpret changes in the horse’s gait and in that respect these tests are subjective and not necessarily consistent between observers.

The recent research study was conducted by orthopedic surgeons based at the University of Glasgow's School of Veterinary Medicine in Scotland. A total of 17 healthy adult horses, all in work, were fitted with sensors before being trotted in a straight line. The sensors measured vertical pelvic movement asymmetry for both right and left hind limb strides and the average difference in maximum and minimum pelvic height between right and left hind limb strides. A hind limb was randomly selected for 60 seconds of proximal flexion, after which the horse was trotted for a minimum of 10 strides. Response to the flexion was blindly assessed as negative or positive by an experienced observer.

John Marshall, BVMS, PhD, Dipl. ACVS, MRCVS, a lecturer in equine surgery at the University of Glasgow and study leader, concluded, “A positive response to flexion resulted in significant changes to objective measurements of pelvic symmetry, supporting the use of inertial sensor systems to objectively assess response to flexion tests.”

Jim Moore, DVM, PhD, North American editor of the EVJ, continued, “The introduction of an objective approach to documenting lameness examination will not only help vets and trainers to investigate equine lameness more accurately. It will also serve as an unbiased method of communicating lameness examination findings among vets, trainers, farriers, and other professionals.”

The next phase of research will be to establish cut-off values for objective assessment of other equine lameness diagnostic procedures, such as nerve blocks.

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